ACTG 382 is a phase I/II, open-label study of a new antiretroviral drug combination (efavirenz plus nelfinavir) in children with HIV infection. This study evaluates this drug combination for its pharmacokinetics, safety, antiviral activity (as measured by changes in plasma HIV RNA level) and effects on immune reconstitution in children ages 3 months to 16 years of age. The treatment duration is 104 weeks. This multicenter study is nearing completion of accrual, and is currently open to accrual only for children in the youngest age cohort (3 months to 8 years of age). Preliminary data show favorable effects on suppression of viral load and acceptable tolerability for this drug combination.